Written by Hari Krishnan
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GitHub Spec Kit Extensions: Incubate, Test, and Distribute Experimental Commands

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This is a summary of the article originally published on LinkedIn.

After introducing the /cross-feature command for cross-feature analysis using Systems Thinking, a challenge emerged: how to share experimental commands, gather feedback, and iterate rapidly without waiting for PR review cycles in the main GitHub Spec Kit repository.

Key Takeaways

  1. Experimental repository enables rapid iteration — The spec-kit-extensions repository (https://github.com/polarizertech/spec-kit-extensions) provides an incubation space for experimental commands that may be context-specific or need community validation before upstreaming to GitHub Spec Kit.

  2. Opt-in approach for specialized commands — Certain commands serve specific workflows or use cases. An extension repository allows teams to try experimental features without committing to them in the core Spec Kit, making innovation more accessible.

  3. Clear naming convention prevents conflicts — Extensions use the /speckit.extn prefix (e.g., /speckit.extn.cross-feature) to differentiate from standard /speckit commands, making it clear which commands are experimental versus core functionality.

  4. Low-friction installation and testing — Users can install extensions with a simple script (./install.sh cross-feature <PATH TO YOUR REPO>), enabling early experimentation without manually copying command files or modifying repository structure.

  5. Feedback loop before upstream integration — The extension framework allows gathering community feedback on naming, flags, and developer experience before proposing changes to the main GitHub Spec Kit, resulting in better-refined features.

Read the full article on LinkedIn →

Originally published on LinkedIn on October 15, 2025